• Proceedings of the KIEE Conference
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• 2005.11a
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• pp.36-38
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• 2005

This study is about how to lower the driving voltage that enables to move the micro droplet by the EWOD (Electro Wetting On Dielectric) mechanism. EWOD is well known that it is used ${\mu}-TAS$ digital micro fluidics system. As the device which is fabricated with dielectric layer between electrode and micro droplet is applied voltage, the hydrophobic surface is changed into the hydrophilic surface by electrical property. Therefore, EWOD induces the movement of micro droplet with reducing contact angle of micro droplet. The driving voltage was depended on the dielectric constant of dielectric layer, thus it can be reduced by increase of dielectric constant. Typically, very high voltage ($100V{\sim}$) is used to move the micro droplet. In previous study, we used $Ta_{2}O_{5}$ as the dielectric layer and driving voltage was 23V that reduced 24 percent compared with $SiO_2$. In this study, we used $BZN(Bi_{2}O_{3}ZnO-Nb_{2}O_{5})$ layer which had high dielectric constant. It was operated the just 12V. And micro droplet was moved within Is on 15V. It was reduced the voltage until 35 percents compare with $Ta_{2}O_{5}$ and 50 percents compare with $SiO_2$. The movement of micro droplet within 1s was achieved with BZN (ferroelectrics)just on 15V.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.99-100
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• 2012

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.571-572
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• 2013

• Journal of Information Display
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• v.11 no.2
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• pp.84-90
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• 2010

This paper presents the effects of a dielectric layer and an electrolyte on the driving performance of an electrowetting on dielectric (EWOD)-based liquid lens. The range of tunable focal length of the EWOD-based liquid lens was highly dependent on the conditions of the dielectric layer, which included an inorganic oxide layer and an organic hydrophobic layer. Moreover, experiments on the physical and optical durability of electrolyte by varying temperature conditions, were conducted and their results were discussed. Finally, the lens with a truncated-pyramid silicon cavity having a sidewall dielectrics and electrode was fabricated by anisotropic etching and other micro-electromechanical systems (MEMS) technologies in order to demonstrate its performance. The lens with $0.6-{\mu}m$-thick $SiO_2$ layer and 10 wt% LiCl-electrolyte exhibited brilliant focal-length tunability from infinity to 3.19 mm.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.297-300
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• 2006

This article discusses about the droplet movement on the super-hydrophobic surface by the electro-wetting on dielectric and the effect of particles on the contact angle as well as the movement is investigated. The movement of droplet, driven by the principle of electro-wetting on dielectric, and the effect of particles are experimentally verified according to the driving voltage and different particles concentrations (fluorescent, charged particles). To increase the contact angle, the super-hydrophobic surface is fabricated and applied to the dielectric layer for the EWOD device. Then its performance is verified and discussed.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.8
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• pp.38-43
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• 2019

Electrowetting on dielectric (EWOD) is a unique method of shape control of small-volume droplets in microfluidic biochips that relies on modification of surface wetting characteristics using electrical methods. In this study, the droplet shape control on various dielectric surfaces by the EWOD and the effect of droplets on the contact angle as well as the shape were investigated. The droplet used in the experiment was on a sample substrate with $5{\mu}l$ of de-ionized water (DIW) using a micropipette, and wettability was measured with a contact angle meter. This study is expected to be helpful for the development of various micro-total-analysis-systems (${\mu}TAS$) and microfluidic systems with MEMS technology.

• 한국전산유체공학회:학술대회논문집
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• 2008.08a
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• pp.30.3-30.3
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• 2008

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.377-378
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• 2010

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.175-176
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• 2006

Electrowetting is prevailing for its various applicability on lap-on-a-chip, and MEMS devices, such as a pump, lens, micro-actuator in the micro-TAS technology. In the usual electrowetting, an AC power is preferred to DC practically. The AC electric field delays the contact angle-saturation, decreases the hysterisis, and is more stable in the view point of dielectric strength. But researches for AC electric field on electrowetting have not been reported very much yet. The different effect of AC on the electrowetting system, especially the effect of a frequency needs to be understood more concretely. In this work, the usual system for electrowetting, water droplet on the dielectric coated electrode (EWOD) is analyzed. Experimental study on the response of contact angles on input frequencies is performed. The simple circuit-model for EWOD system is considered to explain the experimental results. For more concrete understanding, the system is analyzed numerically, where simple AC-conduction model is used. Wetting tensions are analyzed under various input frequency to excavate the experimental results for the responses of the system on input frequencies.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.825-826
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• 2009